Six days later, 11/20, both batches were around SG 0.998, I forgot to write it down so I don't remember the exact SG, but it was under 1. Even though I had left some head space both batches bubbled out of the airlock.
This looks suspicious to me. I've never seen a cider go that fast, and usually see very little foam on top. However I also ferment mine cooler around 55-60 F, and I would recommend you do the same if you can -- draping the fermenter in a wet t-shirt can work wonders in this regard. I think maybe you are fermenting too hot and it is hurting your cider, that or the nutrients are making the yeast work too fast.
You might be in too much of a hurry. One month in the fermenter is pretty fast, and there is surely still yeast suspended in the cider. You can add gelatin to remove most of the yeast, you will probably enjoy the taste of that better too. Or just be more patient and let it sit for 2 or even 3 or 4 months before bottling.
Oxidation is not an issue for your cider at all. Using marbles is a good idea, but for such a fast cider, the odds of it going to vinegar in just 4 or 5 weeks is fairly low.
Did you not treat the raw juice with sulfite or pasteurize it at all? You might have wild yeast in there making it taste not to your liking. Odds are this is NOT an issue for you, but it is possible. I like to pasteurize mine at 160 F for 15 minutes, and I'm considering taking this down to 150 F for 20 minutes to reduce cooked flavors. Then I know that only my chosen yeast is doing the work for me, and not anything wild. Speaking of which...
My favorite yeast is Cote des Blancs. It's the best for cider. There, I've said it, as I've said dozens of times in other threads -- enough said!
Maybe try making cider without the nutrients and see if you like that better. Lack of nutrients is not a bad thing at all in my experience, and will serve to slow the fermentation, quite possibly resulting in a better product.
Remember this rule of thumb: Low and slow is the way to go. Keep temperatures cool, skip nutrients, and try to get the fermentation to go as slow as possible instead of as fast as possible. That's my recipe for a great cider. One last thing -- I like to rack mine after the first few days or when gravity reaches about 1.020, this removes most of the yeast and helps slow things down even more. Sometimes I even add gelatin to help bring fermentation to more of a screeching halt if it's moving too fast. Looks to me like yours moves way too fast for my liking.
Hope this helps. Implementing just one or two of my suggestions, if not all of them, will hopefully bring some improvements to your cider in future.
Cheers.